JPH07281460A - Electrophotographic photoreceptor for transfer of latent image - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic photoreceptor for transfer of latent images excellent in electrification property and sensitivity with high latent image transfer potential by forming the photosensitive layer comprising a specified charge producing pigment and org. acceptor compd. added to a binder. CONSTITUTION:This photoreceptor is produced by directly forming a monolayer org. photosensitive material on a conductive base body or with a base coating layer interposed. This photosensitive layer contains at least a charge producing pigment and org. acceptor compd. expressed by formula dispersed or dissolved in a binder. In formula, R1, R4 are hydrogen atoms, alkyl groups, R2, R3 are hydrogen atoms, alkyl groups, X is at least one group selected from =O, =C(A1)(B1), and =N-R5, wherein each A1, B1 is at least one kind selected from hydrogen atoms, halogen atoms, cyano groups, aromatic groups and -COOR6, R5 is an alkyl group, aromatic group, cyano group, and R6 is an alkyl group or aromatic group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a latent image transfer system, and is particularly suitable for a latent image transfer system for high definition image output. It is about.

[0002]

2. Description of the Related Art Many photoconductor systems and constituent materials are known as photoconductors used in the Carlson process, which is one of the electrophotographic processes. In order to achieve the desired quality requirements, the so-called function separation method, in which the functions of the photoconductor are separated and the functions are shared by several layers with different compositions and components, has become the main method of current photoconductors. ing. By this method, the chargeability, sensitivity, mechanical strength and repeatability of these properties are satisfied to a practically sufficient degree. The background is the development of many materials. In particular, many kinds of organic materials have been filed because of their wide variety of materials and their excellent electrical insulation. As the charge generating substance, for example, phthalocyanine is disclosed in JP-B-49-4.
X-type metal-free phthalocyanine for 338, JP-A-58-7
24 is a π-type metal-free phthalocyanine, JP-A-58-1
82639 has a τ-type metal-free phthalocyanine, JP-A-5-5
1-223738 includes ε-type copper phthalocyanine, Japanese Patent Laid-Open Publication No.
9-49544, titanyl phthalocyanine crystals, JP-A-61-239248, α-type titanyl phthalocyanine, JP-A-62-67094, β-type titanyl phthalocyanine, JP-A-47-37543 as a disazo pigment,
52-4241, 53-95033, 54-727 are disclosed.

As an example of the hole transfer material, Japanese Patent Laid-Open No. 52-1 is used.
24330, 52-139064, oxadiazole compounds, JP-A-55-46760, 55-46761, hydrazone compounds, JP-A-56-119132, benzidine diamine compounds, JP-A-58-65440, 58.
A styryltriarylamine compound in -198043,
JP-A-3-107860 discloses a butadiene-based compound. In addition to the function-separated layered structure well known as the structure of the photoconductor, in JP-A-54-1633, a single-layer photoconductor in which a charge generation pigment is dispersed in a resin together with a donor and an acceptor which are charge transport substances. However, Japanese Patent Application Laid-Open No. 3-256050 has filed an application for a single-layer photoreceptor having the same structure as described above using a diphenoquinone derivative as an acceptor compound.

On the other hand, the latent image transfer method, which is one of the electrophotographic methods, differs from the above-mentioned Carlson method in that a voltage is applied between the photoconductor and an electrostatic recording material capable of holding an electrostatic latent image. In this way, the electrostatic latent image formed on the photoconductor is transferred onto the electrostatic recording body, and then the transferred electrostatic latent image is developed and visualized. This method has been known for a long time. M. Schafert's "Electronic Photography" (Kyoritsu Publishing, 1973), TESI (Latent Image Transfer) on page 70
There is a description of the law. According to it, in the latent image transfer method, an electrostatic latent image is first formed on a photoconductor and then the electrostatic image is transferred onto the electrostatic recording body, and the electrostatic recording body and the photoconductor are brought into contact with each other. There is a direct method of creating an electrostatic latent image in a state. The present invention mainly relates to an electrophotographic photosensitive member suitable for the sequential method.

The latent image transfer method has a drawback that plain paper cannot be used because it requires a conductive layer and a dielectric layer as a recording medium as compared with the Carlson method, but the electrostatic latent image on the photoconductor is directly developed. Since it is not necessary, there is a merit that there is a high margin in designing an apparatus in which various units required for the electrophotographic process are arranged around the electrophotographic photosensitive member. Taking advantage of these merits, a copying machine adopting the sequential latent image transfer method was commercially available at the time of the creation of the electrophotographic apparatus. As an electrophotographic photosensitive member used in such a copying machine, vapor deposition Se is used.
There is a laminated type photoreceptor in which a layer is used as a charge generation layer and polyvinylcarbazole is used as a charge transport layer. However, the photoconductor applicable to a copying machine using such a sequential transfer method does not need to have special characteristics, and the electrophotographic photoconductor for the Carlson method is directly used for the latent image transfer process of the sequential transfer method. Can be used as a photoconductor. On the other hand, in the simultaneous transfer method, since it is required to devise the photosensitive member more than the sequential transfer, for example, JP-A-56-4366 is used.
No. 5, there is an application for providing an insulating layer to meet the demand for high breakdown voltage.

However, in recent years, the latent image transfer method has been reviewed and examined for high quality electrophotographic image output which is difficult with the Carlson method, instead of being opposed to the Carlson method within the range of application of the Carlson method. ing. This is because the latent image transfer method does not require a transfer step after development, and thus has a possibility of obtaining an essentially high-definition and high-quality image as compared with the Carlson method. As a photoreceptor for a latent image transfer system used in such a high quality image output device,
High sensitivity and stability of potential due to repetition are important factors, but especially high transfer potential is required. If the transfer potential is low, the density of the output image will be low. To increase the transfer potential, a transfer voltage may be applied so as to increase the difference between the potential of the photoconductor and the potential of the conductive layer of the recording medium at the time of latent image transfer, but if the transfer voltage is set too high, the image may be lost. This causes a problem that an abnormal image is generated. Further, if the dielectric layer of the recording medium is thickened, the potential of the recording medium is improved, but even in this case, the transferred charge amount does not increase. It is understood that in a system in which the process speed is slowed down to improve the image quality, the development density is mainly determined by the surface charge amount of the recording material, and thus such a measure cannot increase the image density.

In view of the above problems, it is understood that an electrophotographic photosensitive member which can secure a high transfer potential of the electrostatic recording material is desired for the high quality latent image transfer process. However, it has been unclear whether a high transfer potential can be obtained immediately when a conventionally used electrophotographic photoreceptor is used in a latent image transfer process. When the laminated type photoconductor was actually applied to the process, the transfer potential was rather low.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic photoreceptor for transferring a latent image, which is excellent in charging property and sensitivity and has a high latent image transfer potential.

[0009]

According to the present invention, after an electrostatic latent image is formed on an electrophotographic photosensitive member, an electrostatic recording member is brought into contact with the surface side of the photosensitive member, and the photosensitive member and the electrostatic recording medium are contacted with each other. A latent image transfer system that visualizes the electrostatic latent image on the electrostatic recording body after applying a voltage between the electrographic recording bodies to transfer the electrostatic latent image corresponding to the photoconductor onto the electrostatic recording body. In an electrophotographic photosensitive member used in an electrophotographic method, a single-layer organic photosensitive member is provided on a conductive substrate directly or via an undercoat layer, and the photosensitive layer contains at least a charge generating pigment and the following general formula (I ), (IV), (VI
The organic acceptor compound represented by I) is dispersed or compatible with a binder, or an electrophotographic photoreceptor, or an organic hole transporting material has a weight composition ratio to the organic acceptor compound. There is provided the electrophotographic photosensitive member characterized by being added in a range of 1/50 to 5/1. The organic acceptor compound used in the present invention is represented by the following chemical structure.

[0010]

[Chemical 4]

[Wherein R ₁ and R ₄ are the same or different hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted aromatic groups, substituted or unsubstituted heterocyclic groups, substituted or unsubstituted It represents at least one group selected from the group consisting of an alkoxycarbonyl group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted acyl group, a cyano group, a nitro group and a halogen atom. R ₂ and R ₃ are the same or different hydrogen atom, at least one group selected from the group consisting of a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic group, and a substituted or unsubstituted heterocyclic group. Represent. X represents = 0, and represents at least one group selected from the group consisting of groups represented by the following formulas (II) and (III). ═C (A ₁ ) (B ₁ ) (II) ═N—R ₅ (III) (In the above (II), A ₁ and B ₁ are the same or different hydrogen atom, halogen atom, cyano group, substituted or unsubstituted And an at least one group selected from the group consisting of —COOR ₆ and, in the above (III),
R ₅ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic group, or a cyano group. R
₆ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic group. )]

[0012]

[Chemical 5]

[Wherein R ₇ , R ₈ , R ₉ and R ₁₀ are at least one selected from the group consisting of the same or different hydrogen atoms, halogen atoms, substituted or unsubstituted alkyl groups, cyano groups and nitro groups. Represents a seed group. X represents = 0, and represents at least one group selected from the group consisting of groups represented by the following formulas (V) and (VI). ═C (A ₂ ) (B ₂ ) (V) ═N—R ₁₁ (VI) (In the above (V), A ₂ and B ₂ are the same or different hydrogen atom, halogen atom, cyano group, substituted or unsubstituted. And at least one group selected from the group consisting of —COOR _{12. In the} above (VI), R
₁₁ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic group, or a cyano group. R ₁₂
Represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic group. )]

[0014]

[Chemical 6]

[Wherein, X represents = 0, and represents at least one group selected from the group consisting of groups represented by the following formulas (VIII) and (IX). = In _{C (A 3) (B 3} ) (VIII) = N-R 13 (IX) ( wherein _{(VIII), A 3, B} 3 are the same or different hydrogen atom, a cyano group, COOR _14, substituted or unsubstituted Represents a phenyl group, a substituted or unsubstituted naphthyl group, or a substituted or unsubstituted pyridyl group.
In, R ₁₃ represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, or a cyano group. R ₁₄ represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group. )] W represents an alkyl group, a halogen atom, an alkoxycarbonyl group, a phenyl group, a cyano group, or a nitro group. n represents an integer of 0 to 4. ] These substituents will be described with examples.

The substituted or unsubstituted alkyl group for R ₁ and R ₄ in the above formula (I) is a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an n-butyl group,
Hexyl group, alkyl group such as octyl group, cyclohexyl group, cycloalkyl group such as cyclopentyl group, trifluoromethyl group, chloromethyl group, bromoethyl group,
Examples thereof include halogen-substituted alkyl groups such as fluoropropyl group and benzyl group. Examples of the substituted or unsubstituted aromatic group include aromatic groups such as phenyl group, naphthyl group, anthracene group and pyrene group, and the substituents thereof include chloro group, bromo group, methyl group, ethyl group and isopropyl group. Group, t-butyl group, n-butyl group,
Nitro group, cyano group, methoxy group, ethoxy group, acetoxy group, methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, methylcarbonyl group, ethylcarbonyl group, N, N-dimethylamino group, benzooxyamino group, N, Examples thereof include N-dimethylamide group, methylthioxy group, trifluoromethyl group and phenyl group.

As the substituted or unsubstituted heterocyclic group,
Examples thereof include a furan group, a thiophene group, a pyridine group, a benzofuran group, a benzothiophene group, a quinoxaline group, and a piperan group, and as the substituents, a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an n-butyl group, Examples thereof include a chloro group, a bromo group, a nitro group, a cyano group and a methoxycarbonyl group. Examples of the substituted or unsubstituted alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl group, a phenoxycarbonyl group, a 3-chlorobutoxycarbonyl group and a 4-methylphenoxycarbonyl group. As the substituted or unsubstituted carbamoyl group, N, N-dimethylcarbamoyl group, N, N
Examples thereof include a -dihexylcarbamoyl group, an N-ethylcarbamoyl group and an N, N-ditolylcarbamoyl group.

Examples of the substituted or unsubstituted acyl group include methylcarbonyl group, ethylcarbonyl group, hexylcarbonyl group and tolylcarbonyl group. Halogen atoms include fluorine, chlorine, bromine,
Examples thereof include iodine. In R ₂ and R ₃ in the above formula (I), a substituted or unsubstituted alkyl group,
Examples of the aromatic group and the heterocyclic group are the same as those of R ₁ and R ₄ described above. Examples of the substituted or unsubstituted aromatic group represented by A ₁ and B ₁ in the above formula (II) are R mentioned above.
₁ and R ₄ are similar to those examples. Examples of the substituted or unsubstituted alkyl group and aromatic group for R ₅ and R ₆ in the above formulas (II) and (III) are the same as those for R ₁ and R ₄ described above. Specific examples of the compound represented by formula (I) of the present invention are shown in Table 1, but not limited thereto.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

[Table 4]

[0023]

[Table 5]

[0024]

[Table 6]

[0025]

[Table 7]

[0026]

[Table 8]

[0027]

[Table 9]

[0028]

[Table 10]

[0029]

[Table 11]

[0030]

[Table 12]

In R ₇ , R ₈ , R ₉ and R ₁₀ in the above formula (IV), examples of the substituted or unsubstituted alkyl group include a methyl group, an ethyl group, an isopropyl group, a t-butyl group and an n-butyl group. Examples include alkyl groups such as hexyl group and octyl group, cycloalkyl groups such as cyclohexyl group and cyclopentyl group, halogen-substituted alkyl groups such as trifluoromethyl group, chloromethyl group, bromoethyl group and fluoropropyl group, and benzyl group. To be done. Examples of the substituted or unsubstituted aromatic group include aromatic groups such as phenyl group, naphthyl group, anthracene group and pyrene group, and the substituents thereof include chloro group, bromo group, methyl group, ethyl group and isopropyl group. Group, t-butyl group, n-butyl group, nitro group, cyano group, methoxy group, ethoxy group, acetoxy group, methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, methylcarbonyl group, ethylcarbonyl group, N, N Examples thereof include a dimethylamino group, a benzooxyamino group, an N, N-dimethylamide group, a methylthioxy group, a trifluoromethyl group and a phenyl group.

Examples of the substituted or unsubstituted aromatic group for A ₂ and B ₂ in the above formula (V) include aromatic groups such as phenyl group, naphthyl group, anthracene group and pyrene group. Are chloro group, bromo group, methyl group, ethyl group, isopropyl group, t-butyl group, n
-Butyl group, nitro group, cyano group, methoxy group, ethoxy group, acetoxy group, methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, methylcarbonyl group, ethylcarbonyl group, N, N-dimethylamino group, benzooxyamino Examples thereof include a group, N, N-dimethylamide group, methylthioxy group, trifluoromethyl group, phenyl group and the like. The above formulas (V) and (V
Examples of the substituted or unsubstituted alkyl group and aromatic group for R ₁₁ and R ₁₂ in I) are R ₇ , R ₈ and R ₉ mentioned above.
And R ₁₀ are similar to those examples. Specific examples of the compound represented by the general formula (IV) of the present invention are shown in Table 2, but not limited thereto.

[0033]

[Table 13]

[0034]

[Table 14]

[0035]

[Table 15]

[0036]

[Table 16]

In A ₃ and B ₃ in the above formula (VIII),
The substituents on the phenyl group, naphthyl group, and pyridyl group include methyl group, ethyl group, isopropyl group, or t
An alkyl group such as a butyl group, an alkoxy group such as a methoxy group or an ethoxy group, a halogen atom such as fluorine, chlorine or bromine, a halogen-substituted alkyl group such as a trifluoromethyl group, an alkoxycarbonyl group such as a methoxycarbonyl group, Examples thereof include a substituted or unsubstituted naphthoxycarbonyl group, an acyl group, a cyano group and a nitro group. In R ₁₃ and R ₁₄ in the above formulas (VIII) and (IX), examples of the substituents of the phenyl group and the naphthyl group are the same as those of A ₃ and B ₃ mentioned above. As the substituent of the alkyl group represented by R ₁₄ in the above formula (VIII), an alkoxy group such as a methoxy group and an ethoxy group,
Examples thereof include halogen atoms such as fluorine and chlorine. Specific examples of the compound represented by the general formula (VII) of the present invention are shown in Tables 3 and 4, but not limited thereto.

[0038]

[Table 17]

[0039]

[Table 18]

[0040]

[Table 19]

[0041]

[Table 20]

[0042]

[Table 21]

[0043]

[Table 22]

[0044]

[Table 23]

[0045]

[Table 24]

[0046]

[Table 25]

[0047]

[Table 26]

[0048]

[Table 27]

[0049]

[Table 28]

[0050]

[Table 29]

[0051]

[Table 30]

[0052]

[Table 31]

[0053]

[Table 32]

[0054]

[Table 33]

[0055]

[Table 34]

[0056]

[Table 35]

[0057]

[Table 36]

[0058]

[Table 37]

[0059]

[Table 38]

Examples of the charge generation pigment that can be used in the present invention include X-type metal-free phthalocyanine, π-type metal-free phthalocyanine, τ-type metal-free phthalocyanine,
phthalocyanine pigments such as ε-type copper phthalocyanine, α-type titanyl phthalocyanine, β-type titanyl phthalocyanine, disazo / trisazo pigments, anthraquinone pigments, polycyclic quinone pigments, indigo pigments, diphenylmethane, trimethylmethane pigments, cyanine pigments, Quinoline pigments, benzophenones, naphthoquinone pigments, perylene pigments, fluorenone pigments, squarylium pigments, azulenium pigments, perinone pigments, quinacridone pigments, naphthalocyanine pigments, and porphyrin pigments can be used. The amount of these charge generating pigments that can be used in combination with the organic acceptor compound in the entire photosensitive layer is 0.1-40 wt%, preferably 0.3-2.
5% by weight is suitable. As the organic hole transporting substance used in the present invention, known substances can be used, for example, compounds having a triphenylamine moiety in the molecule, hydrazone compounds, triphenylmethane compounds, oxadiazole compounds, carbazole groups. And a pyrazoline-based compound, a styryl-based compound, a butadiene-based compound, a polysilane-based compound having a linear main chain made of Si, and a polymer donor compound such as polyvinylcarbazole. The amount of the organic hole transporting material in the entire photosensitive layer is 10
% Or more, and preferably 20 to 60% by weight.

The present invention will be described in detail below with reference to the accompanying drawings. In FIG. 1A, 1 is a conductive substrate, 2 is a photosensitive layer, 21 is a charge generating pigment, 22 is an organic acceptor compound molecularly dispersed in a binder 23. Further, FIG. 1B shows a photosensitive member to which the organic hole transporting material 24 dispersed in a molecular form is added.
Further, FIG. 2 shows transfer of an electrostatic latent image in the sequential transfer system. In the figure, 3 is an electrostatic recording body, 31 is a dielectric layer of the electrostatic recording body, 32 is a conductive layer of the electrostatic recording body, 4 is a conductive roller,
Reference numeral 5 indicates an applied voltage during transfer. By setting the applied voltage value, a mode in which the charged portion of the photoconductor is transferred (positive transfer) and a mode in which the non-charged or low-charged portion of the photoconductor is transferred (negative transfer) can be selected. Such a photoreceptor of the present invention is excellent in charging property and sensitivity, and when used in a sequential transfer process, it is possible to achieve a sufficient development density at a transfer potential of a recording medium under a transfer condition in which an abnormal image such as a blank area does not appear. It can be as high as that. The reason for this is currently unclear,
Although further studies are needed in the future, high chargeability and high sensitivity also lead to a high transfer potential for the following reasons.

In order to achieve high image quality, it is necessary to carry out each process up to visualization under mild conditions, resulting in a slow process speed. In such a case, it takes a time from charging to transfer. When a photoconductor having a poor charging property is used, the dark decay rate is high, so that the potential contrast between the image portion and the non-image portion is lowered, and the potential contrast on the electrostatic recording after transfer is also lowered. Further, the excellent sensitivity leads to a large potential contrast on the photoconductor and a high potential contrast on the electrostatic recording body. Further, an advantage of using the organic acceptor compound is that both positive and negative charge polarities can be dealt with by changing the compositions of the hole transport material and the organic acceptor compound. The use of organic acceptor compounds also leads to a reduction in residual potential, a longer life of the electrostatic properties of the photoreceptor and a repetitive stabilization of the transfer potential. The cause of these improvements is not clear, but one of them is to prevent the reduction of the internal electrolysis of the charge generating pigment and the decrease of the electric resistance by extracting the electrons out of the holes and electrons generated in the charge generating pigment by light irradiation. Can be considered. When the organic acceptor compound is used, the amount ratio of the hole transport material and the organic acceptor compound is 1/5 or less. When the content of the organic acceptor compound is less than the above range, the repetition of electrostatic characteristics is reduced, and when it is more than this range, the chargeability is deteriorated.

The role of the binder in the photoconductor is not only good dispersion of the charge generating pigment and the molecular dispersion of the transport material, but also the mechanical strength of the photoconductor required in the copying process. However, since the process in which the present photoconductor is used does not require development on the photoconductor, cleaning may be much weaker than that of the Carlson process.
Therefore, the composition of the binder can be lowered in the photoconductor of the present invention as compared with the photoconductor for the Carlson process. As the binder that can be used in the present invention, polyethylene,
Polypropylene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, etc. , Polycondensation type resins, and copolymer resins containing two or more of these repeating units, such as vinyl chloride-vinyl acetate copolymers and vinyl chloride-vinyl acetate-maleic anhydride copolymer resins. it can. The amount of these binders in the entire photosensitive layer is 20 to 90%, preferably 30 to 70% by weight. The thickness of the photosensitive layer of the present invention is preferably 5 to 30 μm. If it is thinner than this range, the charging property is lowered, and if it is thicker, the electrostatic capacity of the photoconductor is lowered and the transfer potential is lowered. Examples of the conductive substrate that can be used in the present invention include metal plates such as aluminum, nickel, copper and stainless steel, metal drums or metal foils, plastic films coated with thin films of aluminum, tin oxide and copper iodide, or glass. Can be mentioned.

In the photoreceptor of the present invention, an undercoat layer may be provided between the photosensitive layer and the conductive substrate for the purpose of improving charging property. As these materials, in addition to the binder material, polyamide resin, polyvinyl alcohol, casein, polyvinylpyrrolidone or the like can be used. In order to produce the photoreceptor of the present invention, the above-mentioned materials are dissolved in an organic solvent or ball mill, and a photosensitive layer-forming liquid prepared by dispersing by an ultrasonic wave is prepared by a known method such as a dipping method, blade coating, or spray coating. The photosensitive layer may be formed by coating on a substrate.

[0065]

EXAMPLES The present invention will be described below with reference to examples, but the embodiments of the present invention are not limited thereby. Example 1 1 g of a phthalocyanine pigment of the following structural formula (A) was ball milled with 10 g of a polycarbonate (PC) solution (10 wt% dissolved in tetrahydrofuran) and 9 g of tetrahydrofuran, and then a pigment composition of 20 wt%, P
15 wt% so that the C composition is 50 wt%, and the organic acceptor compound represented by the compound No. I-2 is 30 wt%.
The PC solution and the acceptor compound were added to prepare a photoreceptor coating solution. This solution was coated on an aluminum substrate by a blade coating method and dried by heating to prepare a single-layer type photoreceptor having a thickness of about 13 μm.

This photoreceptor was corona charged at +6.5 KV in the dark, and when the surface potential after dark decay reached 600 V, 30 lux of tungsten light was irradiated for 1 second. After the light irradiation, the electrostatic recording paper was stuck on the surface of the photoconductor, and the recording paper was peeled from the photoconductor while applying a voltage of +800 V to the conductive layer of the electrostatic recording paper with a conductive roller. When the surface potential on the electrostatic recording paper was measured, -116V was obtained. Due to the electrostatic capacity of the electrostatic recording paper, this potential has a surface charge density of 8.2 × 10.
It was found that a surface charge density corresponding to ^-8 C / cm ² and sufficient for development was reached. When the transfer potential was measured on the unexposed portion under the same conditions, the transfer potential was 0 V.
Met. The measurement was repeated 100 times to examine the change in the transfer potential, and the decrease in the transfer potential was less than 5V.

[0067]

[Chemical 7]

Examples 2 to 3 Photosensitive layers were prepared in the same manner as in Example 1 except that the organic acceptor compound in Example 1 was changed, and the transfer characteristics were measured. The results shown in Table 5 were obtained.

[0069]

[Table 39]

Examples 4 to 14 By changing the organic acceptor compound of Example 1 and further adding a hole transfer agent represented by the following structural formula (B), the pigment composition was 10 wt%, the PC composition was 50 wt%, and the organic compound was organic. A coating solution was prepared so that the acceptor compound was 20 wt% and the hole transporting agent was 20 wt%, and a photosensitive layer was prepared and transfer characteristics were measured in the same manner as in Example 1. The results shown in Table 6 were obtained.

[0071]

[Chemical 8]

[0072]

[Table 40]

Example 15 A photosensitive layer was prepared and transfer characteristics were measured in the same manner as in Example 4 except that the bisazo pigment represented by the following structural formula (C) was used instead of the pigment of Example 4. Transfer potential is -173 in exposed area
At V and 0 V in the unexposed area, the decrease in transfer potential after repeating 100 times was also less than 5 V.

[0074]

[Chemical 9]

Examples 16 to 25 Photosensitive layers were prepared in the same manner as in Example 4 except that the organic acceptor compound in Example 15 was changed, and the transfer characteristics were measured. The results shown in Table 7 were obtained.

[0076]

[Table 41]

Comparative Example 1 A photoconductor was prepared in the same manner as in Example 4 except that the organic acceptor compound of Example 4 was omitted. When the same evaluation as in Example 1 was performed, the initial transfer potential was 0 in the unexposed area.
V was −90 V in the exposed area, but it was found that the transfer potential of the exposed area dropped to −60 V after 100 times of repetition. Comparative Example 2 A charge generation layer made of phthalocyanine used in Example 1 and a resin (1/1 by weight ratio) used in Example 1 was formed on the substrate of Example 1 in an amount of about 0.
5 μm was provided. On top of that, 1 g of the organic acceptor compound used in Example 1 and 1 g of resin were added with tetrahydrofuran 18
A liquid dissolved in g was applied to provide a 12 μm charge transport layer. When the transfer potential of this photosensitive member was measured in the same manner as in Example 1, the result was -40 V in the unexposed area and 0 V in the exposed area.

[0078]

INDUSTRIAL APPLICABILITY In the single-layer type electrophotographic photoreceptor of the present invention, at least the charge generating pigment compound and the organic acceptor compound are dispersed in the binder, or in addition thereto, the organic hole transporting substance is added. When used in an electrostatic transfer process by using a compound represented by the general formula (I), (IV) or (VII) as an organic acceptor compound,
It was found that a high transfer potential was obtained and the durability was excellent.

[Brief description of drawings]

FIG. 1 is a photoreceptor including a molecularly dispersed organic acceptor compound and a photoreceptor to which a molecularly dispersed organic hole transport material is added.

FIG. 2 is a diagram showing transfer of an electrostatic latent image in a sequential transfer method.

[Explanation of symbols]

 1 Conductive Substrate 2 Photosensitive Layer 21 Charge Generating Pigment 22 Organic Acceptor Compound 23 Binder 24 Organic Hole Transport Material 3 Electrostatic Recording Material 31 Dielectric Layer 32 Conductive Layer 4 Conductive Roller 5 Applied Voltage

Front Page Continuation (72) Inventor Tetsuro Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd. (72) Inventor Masao Yoshikawa 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd. (72) Inventor Emi Kawahara 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd. (72) Inventor Masayuki 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd.

Claims (5)

[Claims] 1. An electrostatic latent image is formed on an electrophotographic photosensitive member, and then an electrostatic recording member is brought into contact with the surface side of the photosensitive member, and a voltage is applied between the photosensitive member and the electrostatic recording member. Then, an electrostatic latent image corresponding to the photoconductor is transferred onto the electrostatic recording body, and thereafter, an electrostatic latent image transfer type electrophotographic method for visualizing the electrostatic latent image on the electrostatic recording body is used. In a photoreceptor, a single-layer organic photosensitive layer is provided on a conductive substrate directly or through an undercoat layer, and the photosensitive layer is at least a particle-like dispersed charge generating pigment and the following chemical structural formula. An electrophotographic photoreceptor for transferring a latent image, wherein the organic acceptor compound represented by (I) is added to a binder. [Chemical 1] [Wherein R ₁ and R ₄ are the same or different hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted aromatic groups, substituted or unsubstituted heterocyclic groups, substituted or unsubstituted alkoxycarbonyl groups] Represents a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted acyl group, a cyano group, a nitro group, or at least one group selected from the group consisting of halogen atoms. R ₂ and R ₃ are the same or different hydrogen atom, at least one group selected from the group consisting of a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic group, and a substituted or unsubstituted heterocyclic group. Represent. Here, R ₁ and R ₂ may be combined to form a ring, and similarly, R ₃ and R ₄ may be combined to form a heterocycle together with a nitrogen atom. Also, these rings may be substituted. X represents = 0, and represents at least one group selected from the group consisting of groups represented by the following formulas (II) and (III). ═C (A ₁ ) (B ₁ ) (II) ═N—R ₅ (III) (In the above (II), A ₁ and B ₁ are the same or different hydrogen atom, halogen atom, cyano group, substituted or unsubstituted And an at least one group selected from the group consisting of —COOR ₆ and, in the above (III),
R ₅ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic group, or a cyano group. R
₆ represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic group. )] 2. The electrophotographic photoreceptor for latent image transfer according to claim 1, wherein a compound represented by the following general formula (IV) is used as the organic acceptor compound. [Chemical 2] [Wherein R ₇ , R ₈ , R ₉ and R ₁₀ are at least one group selected from the group consisting of the same or different hydrogen atoms, halogen atoms, substituted or unsubstituted alkyl groups, cyano groups and nitro groups. Represents X represents = 0, and represents at least one group selected from the group consisting of groups represented by the following formulas (V) and (VI). ═C (A ₂ ) (B ₂ ) (V) ═N—R ₁₁ (VI) (In the above (V), A ₂ and B ₂ are the same or different hydrogen atom, halogen atom, cyano group, substituted or unsubstituted. And at least one group selected from the group consisting of —COOR _{12. In the} above (VI), R
₁₁ represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic group, or a cyano group. R ₁₂
Represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic group. )] 3. The electrophotographic photoreceptor for transferring a latent image according to claim 1, wherein a compound represented by the following formula (VII) is used as the organic acceptor compound. [Chemical 3] [In the formula, X represents = 0 and represents at least one group selected from the group consisting of groups represented by the following formulas (VIII) and (IX). = In _{C (A 3) (B 3} ) (VIII) = N-R 13 (IX) ( wherein _{(VIII), A 3, B} 3 are the same or different hydrogen atom, a cyano group, COOR _14, substituted or unsubstituted Represents a phenyl group, a substituted or unsubstituted naphthyl group, or a substituted or unsubstituted pyridyl group.
In, R ₁₃ represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, or a cyano group. R ₁₄ represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted phenyl group. )] W represents an alkyl group, a halogen atom, an alkoxycarbonyl group, a phenyl group, a cyano group, or a nitro group. n represents an integer of 0 to 4. ] 4. An electrostatic latent image is formed on an electrophotographic photosensitive member, and then an electrostatic recording member is brought into contact with the surface side of the photosensitive member, and a voltage is applied between the photosensitive member and the electrostatic recording member. Then, an electrostatic latent image corresponding to the photoconductor is transferred onto the electrostatic recording body, and thereafter, an electrostatic latent image transfer type electrophotographic method for visualizing the electrostatic latent image on the electrostatic recording body is used. In the photoreceptor, a single-layer organic photosensitive layer is provided on a conductive substrate directly or via an undercoat layer, and the photosensitive layer is a particle-like dispersed charge generating pigment, an organic acceptor compound and an organic compound. 4. The electrophotographic photoreceptor for transferring a latent image according to claim 1, wherein the hole transport material is composed of a binder added to the binder. 5. The weight composition ratio of the organic acceptor compound and the organic hole transporting material forming the photosensitive layer is 1/50.
The electrophotographic photoconductor for transferring a latent image according to claim 4, wherein the electrophotographic photoconductor is between 5 and 1/5.